Reactance device



Aug. 10, 1948. R ALLISON 2,446,624

REACTANCE DEVICE Filed April l0, 1946 10a I4 INVENToR.

Patented Aug. 10, 1948 REACTANCE DEVICE Leslie..R..Allison, ForestHills, Pa., assgnor to The UnionSWitch. & Signal Company, Swissvala.Pa., .acorporation of Pennsylvania Application'April 10, 1946, SerialNo. 660,961"

1^.'Claim. l MyY invention :relates ztoreactance devices, andparticularly to reactors ofithe iron core type.

When'aniron core reactor: is usedwith a fixed.' capacite-nceI to obtain:resonance'. at" azgiven frel quency, the -methc'dfoi tuninglisuallyfollowed is tolkeep thenumber of'turns in the reactor fixed and-vary the.ain gap fin lthe reactor core.

One object' oflmyinvention'is to provide novel and' improved meansfto.permit readyV and accurate adjustment' ofthe air 'gap in'the-core'of areactor of .the typef described inafmanner which will enable thecircuitinrwhich the reactor is to be used to be quickly tuned to'exactresonance.

My present invention .isfan-improvement upon that described in .myyprior-'Patent No. 1,869,364, granted' cn=April .2, 1932,v for areactor.`

Accordingto my'invention, the reactor core is made up of' twocore'membors monntedwith their leg. ends confronting each other-so astofform an air'gap between them.' Attached to each core n member: isapost providedwithia screw threaded hole which aligns Yaxially with" ayhole in a postattached to the other core member. The screw threadedholes receive threaded portions provided on the opposite ends 'ofanadjusting screw or stud in such manner that by turning the adjustingscrew in one direction the core'members will be forced apart, whereas byturning the adjusting screw in the other direction the core members willoe-'pulled together. Theidesired adjustment can be made by threading thetwo ends ofthe screws in opposite directions with very fine pitchedthreads, but thebest results. are obtained when the two endsofthescrerfs: are threaded'in the same directions withthreads havingdiierent pitches as will appear hereinafter.

Other objects and characteristic features of my invention will becomeapparent as the description proceeds.

I shall describe one form of reactor embodying my invention, and shallthen point out the novel features thereof in claims.

In the accompanying drawings, Figs. 1 and 2 are side and end elevationalviews, respectively, showing a reactor provided with adjusting meansembodying my invention.

Similar reference characters refer to similar parts in both views.

Referring to the drawing, the reactor here shown comprises a shell typeiron core made up of two three legged core members I and 2 mounted withtheir legs I c2c, Ib2b and le20 in confronting relation in such mannerthat by moving the core members apart air gaps can be provided betweenthe leg ends to vary the CFI permeability of thecore, as willbe obvious.The two core members may be'alike, and'eaclrcomY- prises ay plurality ofE-shaped laminations clamped as by riveting betweentwo non-magmeticy endbrackets 3. The central-core legsl Ib2b are# surrounded bi/ a'winding 4.This winding may be either asingle reactor winding or the primary' andsecondary windings of a reactance type transformer. it will loe-apparentthat the in'- ductance of the winding twill depend upon thepermeabilityy of the core, and may therefore readily be variedbyvaryingthe air gaps between` the core legs.

In accordancev with'my'present invention, in order Vto conveniently and"easily effect an accurate and precise' adjustment ofthe' airgaps betweenthe core legs, I provide `at one end of the core two adjusting screws orstuds Sand 6. These' screws are threadedat each end, and the one screw-5 is screwed" at itsl ends. into aligned threaded holes 'laand'a'providedin corner postsv I and 8 secured respectively to the coremembers I and 2` at one side ofI the. core .while'the other adjustingscrew `i5 is screwed'. at its ends into threaded holes gaand'. Iaprovided in corner posts 9 and I0 secured .respectively to the coremembers I and `2 'at the other side of the. core. The corner posts maybesecured to the associated i core members in any desired manner, but ashere shown they are secured to the core members by integral shankportionswhich extend. through apertured lugs II provided on theclampingV brackets 3 'and receive nuts I2 screwed onto the threaded endsof the shank portions of the corner posts. The threadedshank portions ofthe corner posts are preferably machined for a snug fit in the aperturesin the lugs II to preclude the possibility of changes taking place inthe core adjustment after an adjustment has once been made.

The threads on the opposite ends of the adjusting screws are so arrangedthat by turning the adjusting screws in one direction the core members Iand 2 will be forced apart, whereas by turning these screws in the otherdirection the core members will be pulled together. To facilitateturning the screws the central shank: portions of the screws arepreferably made polygonal in shape to provide a wrench grip, and may inaddition be drilled with one or more holes i3 to receive the end of arod. Furthermore, if desired a saw lrerf I4 or the like may be providedin either 0r both ends of the adjusting screws for the reception of ascrew driver.

The adjusting screws may if desired be threaded at .their opposite endsin opposite directions with very nne pitch threads, but the bestresul-ts are obtained when the two ends of the screws are threaded inthe same direction but with threads having different pitches. Forexample, one end of each screw m-ay be provided with 24 threads per inchand the other end of Aeach screw with 32 threads per inch in which eventone complete revolution of the adjusting screw will result in a changein the distance between the corner posts into which the screw is screwedequal to the differences between r and 31E of an inch or 0.0104 inch.The change in mean air gap for the core as a whole will be considerablyless bec-ause of the proportional distance of the air gaps from the meancenter line of movement.

An adjusting screw assembly similar to either of those just describedmay be applied to one, two, three or four corners of the reactor core,if desired. In practice, however, it will usually be found sufiicient toprovide only two adjusting screw assemblies at one end of the core asshown, and to clamp the cores together at the other end with a xedspacer between the adjacent core legs. The means illustrated forclamping the cores together is Well known, and comprises two clampingbolts I1 (only one of which is visible inthe drawing) which pass throughaligne-d holes I8 provided in laterally projecting lugs I 9 form-ed onthe clamping brackets on each side of the core. y,

It should be particularly pointed out that with the adjusting meansconstructed in the manner described the air gaps between the ycore legscan be adjusted continua-ily .and precisely by turning the adjustingscrews either by means of a wrench placed on .the central shank portionsof the screws, or by means of a length of rod inserted in one of the twoholes I3 drilled at right langles to each Iother in the central shankpontion's of the screws, or by means of a screw driver inserted in thesaw kerf I4 at either end of the adjusting screws. The large number ofthreads of small clearance in engagement between the adjusting screwsand associated lugs makes further locking unnecessary after tuning isaccomplished. If desired, however, any possible play in the threads canbe taken up by providing additional clamping bolts at the ends of thecore nearest the adjusting screw similar to those provided at the otherend of the core, or clamping nuts may be placed on the adjusting screwsbetween the central shank portions and .the associated 4corner posts.These nuts when provided would be loosened before an adjustment is made,and tightened upon completion of the adjustment. After an ad- -4justment has been made wire seals can be threaded .through the holes I3in the adjusting screws to prevent unauthorized changing of the air gapadjustment.

It should be clearly understood that While I have shown my inventionapplied to a three legged core of the shell type, it can readily beapplied to any core having relatively-movable core members, relativemovement of which is desired to enable Ithe air gap between the coremembers to be varied.

Although I have herein shown and described only one form of the reactordevice embodying my invention, it is understood A.that various changesand modifications may be made therein within the scope of the appendedclaim without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

In a reactance device comprising two core members separated by an airgap which can be adjusted to vary the reactance of said device by movingone core member relative to the other, the means for moving said onecore member relative to said other core member to eect an accurate andprecise adjustment of said air gap comprising a rst post memberremovably secured to one of said core members, a second post memberremovably secured to the other said core member, and an adjusting memberprovided with a screw threaded connection with each of said first andsecond post members in such manner that by .turning said adjustingmember said core members may be moved relative to each other to vary theair gap between them, said threaded connections being threaded in thesame directions with threads having different pitches, whereby thechange in air gap which results from each revolution of said adjustingmember will be a func-tion of the diierence in pitch between the threadson said threaded connections.

LESLIE R. ALLISON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 83,225 Tudor Oct. 20, 18681,637,404 Hunt Aug. 2, 1927 1,925,224 Alder Sept. 5, 1933 1,991,400Littmann Feb. 19, 1935 2,086,316 Holslag July 6, 1937

